The invention relates to an internal combustion engine having a bypass line skirting the load-control organ of the internal combustion engine in which a regulating device is arranged, controlling the bypass line, which is constructed by an auxiliary air valve controlled through a control line in dependence of the suction pipe vacuum and that the internal combustion engine is provided with, for example, an air-measuring, drive-less injection installation with continuous fuel supply and partially exhaust burning unit according to commonly assigned U.S. patent application Ser. No. 719,706, filed Sept. 2, 1976, now U.S. Pat No. 4,084,565 which is incorporated by reference to the extent necessary for a full understanding of the present invention.
Internal combustion engines with injection installations of the mentioned kind (Bosh, Technische Unterrichtung Benzineinspritzung K-Jetronic, 1st Issue, February 1974) in which, during the warm-operation phase of the internal combustion engine, a larger quantity of fuel-air mixture must be supplied to the internal combustion engine than corresponds to that achieved as a result of the position of the load-regulating device in order to compensate for the friction load occurring in this phase of operation. This is accomplished by the auxiliary air slide bypassing the load-regulating device. The cross section of the slide is regulated by an apertured partition controlled in dependence of the heating of an electrically heated bimetal strip which is closed when a warm operating condition of the internal combustion engine is achieved. Nevertheless, it has been proven disadvantageous that the additional quantity of fuel-air mixture, which is adequate during the warm-operation phase after the starting process has not always been found sufficiently large during the starting process whereby, among other things, a sure start and a quick high operating speed of the internal combustion engine to idling speed is not assured.
To avoid this disadvantage, it is known from the above-noted Ser. No. 719,706 that the regulating organ controlling the bypass line is constructed by means of an auxiliary air valve controlled in dependence of the suction pipe vacuum. In one exemplified embodiment, the auxiliary air valve is provided with a valve plate connected to a membrane which opens and closes the bypass line whereby, through the bypass line, the suction pipe vacuum acts at one side of the membrane ahead of the load-regulating organ and, through a control or regulating line, the suction pipe vacuum acts at the other side of the membrane behind the load-regulating organ, and that at the side of the membrane admitted by the suction pipe vacuum, a compression spring is provided. By this means, a sure start of the internal combustion engine and a quick increase to a high rotative speed is assured; however, as a result of the increasing suction pipe vacuum, the bypass line is closed by the auxiliary air valve before the exhaust after-burning arrangement reaches the temperature sufficient for the exhaust after-burning.
It is therefore an object of the present invention to decrease the time which is necessary until the temperature of the exhaust after-burning device required for the exhaust after-burning is reached.
According to a preferred embodiment, this problem is solved in that a thermo-switching valve is arranged in the control line regulating the opening cross section of the control line.
By means of the thermo-switching valve, the bypass line is held open also with increasing suction pipe vacuum for a predetermined time by the regulating organ, so that throughout this time, a larger quantity of fuel-air mixture is supplied to the internal combustion engine than corresponds to that achieved as a result of the position of the load-regulating organ. This operating phase of the internal combustion engine with increased rotational speed after a cold start effects a higher exhaust temperature which leads to a quick attainment of the temperature of the exhaust after-burning installation necessary for the exhaust after-burning.
These and further objects, features and advantages of the present invention will become more obvious from the following description when taken in connection with the accompanying drawings which show, for purposes of illustration only, a single embodiment in accordance with the present invention.